A facile strategy is developed to synthesize the novel attapulgite/poly(acrylic acid) nanocomposite (ATP/PAA) hydrogels via the “one-pot” inverse suspension polymerization with the multifunctionalized attapulgite (org-ATP) as the unique cross-linker. The org-ATP is in situ produced directly in the form of water-in-oil emulsion and then used as prepared for the inverse suspension polymerization without being separated; so the proposed strategy is much simpler compared with the traditional methods. Almost all acrylic acid (AA) monomers have been successfully grafted onto ATP to form the 3-dimensional cross-linking network of the nanocomposite hydrogels, in which the org-ATP nanorods, as cross-linker and structural strengthening agent, drastically improves the mechanical stability of the resulting ATP/PAA hydrogels. The nanocomposite hydrogels exhibit selective adsorption toward the Pb(II) ion with a maximum adsorption capacity of 42 mg/g, and the adsorbed Pb(II) ion could be eluted completely. The optimized nanocomposite hydrogel adsorbent also exhibits an excellent reusability. The adsorption capacity and desorption rate remain unchanged for at least 10 cycles of adsorption−desorption. These strong points make it a potential adsorbent for heavy metal-contaminated water.